PROJECT SUMMARY: OVERALL This Program Project Grant on remaining critical issues concerning the molecular and biologic control of von Willebrand factor in von Willebrand disease. This PPG is comprised of 4 projects and 3 cores that are all focused on von Willebrand disease and mechanisms causing its dysfunction, increased clearance or increased synthesis, and the role carbohydrate modification play in VWF biology. While this represents a new PPG application, this PPG makes use of the samples and biodata from the pre-existing PPG on historically diagnosed subjects and an R01 grant on new VWD subjects recruited prospectively. Project 1 includes aims to define longitudinal changes in VWF concentration and changes in semiquantitative bleeding assessment during follow-up intervals, the fidelity of the diagnosis of type 2 VWD, the frequency of antibodies to VWF in type 3 VWD, and the development of animal models of VWD and VWD variants. Subjects with low von Willebrand factor (LVWF), and type 1 or 3 VWD with no sequence variants will be studied in Core B with full genome sequencing. Abnormalities identified will be sought in their family members through Project 1 and the mechanism studied by projects 1, 2, 3, or 4 based on candidate pathway. Project 2 will define the role of carbohydrate modification of VWF through determination of N- and O-glycan profiles, study the glycan differences in plasma, endothelial and platelet VWF, and racial differences using MS-glycomic and glycoproteomic approaches. Model systems will be set up in mice to mirror the changes found in human mechanisms. Project 3 will examine the upstream regulatory control as a mechanism causing VWD. The cell biology of VWF will be studied using BOECs obtained from patients with VWD and used to examine the role of promoters and enhancers. Genetically engineered mice will study the mechanisms by which clearance receptors alter VWF concentration. Project 4 will study the transcription regulation of VWF and the inhibition with microRNAs. This project will also examine the role of epigenetics in modulating plasma VWF and the effect of chronic inflammation on these mechanisms. There are three cores to support this PPG. Core A is the administrative core that will facilitate exchange of information, data, and patient samples and biodata. It will also oversee the 10 Primary Clinical Centers that will be following our enrolled subjects. Core B will be doing whole genome sequencing of subjects with very low or absent VWF that have had normal VWF sequencing. Core C will develop animal models for each of the projects to further their studies on VWD mechanisms. Together these studies will comprehensively study unique mechanisms that lead to reduced or abnormal VWF in VWD.